Why the need for such light stocking in marine tanks?

fishperson100

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Hi everybody!

I feel like this is a silly question, but I am going to ask it anyway. So, how come you have to stock marine tanks light than fresh and coldwater tanks? Do they just produce a lot more waste?

Thanks!

- Fishperson100
 

Colin_T

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Seawater holds less oxygen than freshwater and warm seawater holds less oxygen than cool seawater. So a tropical marine tank has less dissolved oxygen in the water than a cold water marine tank.

Seawater has a very alkaline ph (8.5) and any ammonia produced in this water is extremely toxic due to the high pH. Good filtration is essential to remove the ammonia asap so it doesn't harm the fish. fewer fish means less ammonia produced and less stress to the inhabitants.

Lots of marine fish grow big so their end size might be taken into consideration when stocking a tank.

Marine tanks often contain shrimp, crabs, starfish, corals, etc and they add to the bio-load.

Marine tanks often have lots of rocks in them and that displaces some water. Less water means less fish.

They don't produce any more waste than a similar sized freshwater fish, so that is not relevant.
 
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fishperson100

fishperson100

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Thanks! One more question. So if you are stocking a marine tank, would one shrimp or crab or whatever count as a fish? Like, if you were only able to put like 5 fish in a tank, would it have to be like 4 fish and one shrimp?
 

Colin_T

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It depends on the shrimp. Some shrimp and tiny, less than 1 inch long and 3 or 4 of these one inch long shrimp would equal 1 inch of fish. But there are bigger crustaceans too like lobster/ crayfish and they equal a lot more fish.

If you are thinking of setting up a marine tank, you can get trickle filters/ sumps that get joined to the main tank by tubing/ pipes and that can increase the water volume and let you keep more fish in the tank. Basically you have 2 tanks on one stand. One tank above the other. The water flows from the top tank into the bottom tank and is pumped back up to the top tank with a water pump.

If you have 2 tanks the same size set up on a double tier stand and connected, the top tank can be the display tank and house the fish and other organisms. And the bottom tank holds extra water to increase the total volume of water for the fish.
 

SantaMonica

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I think it's more to do with the mindset of the SW person. They are usually about the decor+fish+coral, but the FW person is more about just the fish. So, they get more of them.
 

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